1. Field of the Invention
The present invention relates to an inverter which supplies a driving voltage to an external electrode fluorescent lamp.
2. Description of the Related Art
In recent years, liquid crystal displays capable of reducing in thickness and increasing in size have become popular in place of cathode ray tube displays. In a liquid crystal display, a plurality of cold cathode fluorescent lamps (hereinafter, referred to as CCFL) or external electrode fluorescent lamps (hereinafter, referred to as EEFL) are arranged on the back of a liquid crystal panel in which video is displayed and are made to emit light as a backlight.
For driving the CCFL or EEFL, there is used an inverter (DC (direct current)/AC (alternating current) converter) which boosts, for example, a DC voltage of approximately 12 V and outputs as an AC voltage. The inverter converts an electric current flowing in the CCFL to a voltage and feeds back to a control circuit, and performs ON/OFF control of a switching element on the basis of the fed-back voltage. For example, a driving technique of the CCFL based on such an inverter is disclosed in Patent Document 1 (Japanese Patent Application (Laid open) No. 2003-323994).
There is a problem in that an EEFL is difficult to be lighted as compared with other fluorescent lamps such as a CCFL. As to whether or not the EEFL is lighted, it depends on probability event; and therefore, conventionally, lighting probability is raised by repeating a starting operation of the inverter several times in order to light the EEFL. More specifically, in the known inverter, a high voltage is applied to the inverter for the purpose of striking the EEFL, and an operation that performs shutdown is repeated.
In the known technique, in addition to a control circuit of the inverter, an externally mounted circuit needs to be provided for repeating the shutdown and the starting operation of the control circuit; and therefore, there is a problem in that it becomes large in circuit area or it becomes high cost.